After Institutional Review Board approval, ten patients (two boys and eight girls, mean age 13.3 years) with AIS from the existing outpatient clinic of J. Richard Bowen, M.D. at the Alfred. I. duPont Hospital for Children agreed to participate in the study (Table ). Inclusion criteria for patients in this study were AIS, treatment with the Wilmington scoliosis brace, and agreement to keep a daily manual diary of brace wear. The Wilmington brace is a custom brace made of low-temperature plastic. Prescribed regimens for brace wear time were 8 (night time) or 12 h per day, depending on the severity of the scoliosis.
Patient demographics and curve characteristics
The Cricket is a novel compliance sensor designed by this group from the ground up specifically for this purpose. It is 3 cm in diameter and 1 cm in thickness. It is a self-contained circuit that includes a thermistor for temperature sensing, sufficient memory to record 9 months at one reading every 10 min, and an LCD readout that displays the average daily wear time (Fig. ). The sensor was placed in the lumbar mold cavity, putting it on the outside of the brace. The thermistor protrudes from the sensor, allowing it to go into a hole in the brace so that it is flush with the inside of the brace. The Cricket was attached and launched at the initial visit and removed after approximately 1 month of brace wear, at which time the data were downloaded and the manual brace wear diary was collected. The data were downloaded wirelessly from the Cricket.
a Shows the front and back of the cricket sensor. b Cricket mounted on the lumbar mold
The custom-designed software (Creative Micro Designs, Newark, DE) for the Cricket allows the retrieval of temperature data, which is converted to an Excel file. This file includes the date of launch, days worn, average daily wear in hours, and graphs daily brace wear and a graph that shows the percentage likelihood of the subject wearing the brace at a given time in a 24-h period. This is shown in Fig. for one of the subjects.
Brace-wearing profile of a typical subject. The y-axis represents the number of days worn, expressed as a percentage of the total days. The x-axis is the time in a 24-h period
The graph in Fig. shows that this patient only wore the brace at night. Peak wearing time was around 1:00 a.m., when she wore it only 50% of the total number of days. The compliance drops off at other times during the night, which indicates that the brace was taken off during the night for some of the nights. Ideally, one would like to see a square-shaped graph with an amplitude of 100% for the duration of the prescribed wear time (Fig. ). This would indicate that the patient wore the brace every day for the prescribed period. Subjects were also asked to keep a manual diary of wear times for a 1-month period.